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Add getenv_strict variant #10

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Add getenv_strict variant #10

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15 changes: 12 additions & 3 deletions src/ppx_getenv.ml
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Original file line number Diff line number Diff line change
Expand Up @@ -2,18 +2,27 @@ open Ppxlib

let getenv s = try Sys.getenv s with Not_found -> ""

let expander ~loc ~path:_ = function
let getenv_strict ~loc s =
try Sys.getenv s
with Not_found -> Location.raise_errorf ~loc "[%%getenv_strict] not set: %s" s

let expander ~strict ~loc ~path:_ = function
| (* Should have a single structure item, which is evaluation of a constant string. *)
PStr [{ pstr_desc =
Pstr_eval ({ pexp_loc = loc;
pexp_desc = Pexp_constant (Pconst_string (sym, _, None)); _ }, _); _ }] ->
(* Replace with a constant string with the value from the environment. *)
Ast_builder.Default.estring ~loc (getenv sym)
Ast_builder.Default.estring ~loc (if strict then getenv_strict ~loc sym else getenv sym)
| _ ->
Location.raise_errorf ~loc "[%%getenv] accepts a string, e.g. [%%getenv \"USER\"]"

let extension =
Context_free.Rule.extension
(Extension.declare "getenv" Expression Ast_pattern.(__) expander)
(Extension.declare "getenv" Expression Ast_pattern.(__) (expander ~strict:false))

let extension_strict =
Context_free.Rule.extension
(Extension.declare "getenv_strict" Expression Ast_pattern.(__) (expander ~strict:true))

let () = Ppxlib.Driver.register_transformation ~rules:[extension] "ppx_getenv"
let () = Ppxlib.Driver.register_transformation ~rules:[extension_strict] "ppx_getenv_strict"